Incandescent lamp



Aug. 16, 1938. c. J. MARTlN INCANDESCENT LAME Filed-oet. 2o, 192s Patented Aug. 16, 1938 UNITED STATES PATENT OFFICE INCANDESCENT LAMP Application October 20,

Claims.

This invention relates to incandescent lamps and has particular relation to lamps having short-circuting devices embodied therein.

A serious difculty in the use of incandescent 5 lamps in series circuits has heretofore arisen by reason of the fact that an open circuit occurring in one of the lamps due to a ruptured lament or the like causes all of the lamps in the series circuit to be extinguished. Upon the occurrence m of such a condition it is necessary to test each of the lamps in the series circuit to determine which one of them has become open circuited. Up to the present time this testing has been done by removing each of the lamps in the series cirl, cuit and replacing them with new lamps until the defective lamp has been located. Such testing requires a considerable amount of time, since each circuit usually includes ve or more lamps.

The present invention overcomes the above described diiculty by providing means embodied in each lamp to short-circuit the same. Each of the lamps in the series circuit may be individually manipulated in sequence until the defective lamp is located. When the defective lamp is so manipulated, the circuit through the remaining lamps will be reestablished and will cause them to burn, whereupon the defective lamp may be removed and replaced by a new lamp with a minimum expenditure of time.

The present invention further contemplates the provision of the above described short-circuiting means in so-called theft-proof lamps, that is, lamps. which are provided with means for preventing their unauthorized removal from their sockets. Such means are well known in the art and do not require detailed description herein. Lamps of this character are frequently so constructed that it is necessary to break the lamp bulb before the base can be removed from the socket. This makes it impossible to remove a usable lamp from its socket, and, therefore, removes any incentive for stealing the lamps.

Heretofore it has been considered entirely impractical to utilize theft-proof lamps in series circuits because the failure of one lamp in a series circuit would frequently necessitate the destruction and replacement of all or nearly all of the lamps in that circuit. The lamps could not be individually removed for testing in the manner described above without destroying each of the lamps so removed, and, therefore, it was supposed that a very considerable loss due to breakage must be involved if lamps of this character were used in series circuits.

According to the present invention, suitable 1928, Serial No. 313,660

short-circuiting means are embodied in theftproof lamps as well as in other types of incandescent lamps, whereby each lamp may be tested without removing it from its socket.

It will be understood from the above that the principal object of this invention is to provide means whereby incandescent lamps may be tested with a minimum expenditure of time and with a minimum loss of lamps. Other objects and advantages of the invention will appear from the following detailed description, taken in connection with the accompanying drawing, in which:

Figure 1 is a view, partly in elevation and partly in section, of a lamp embodying the invention; and

Fig. 2 is an enlarged sectional View taken on the line II-II of Fig. 1.

Referring to the drawing, a lamp embodying the invention comprises a bulb II in which a filament I2 is suitably supported. A conducting lead i3 is connected to one end of the lament I2 and extends outwardly through the base of the bulb I I and is connected to a metallic sleeve or cap ld of the lamp base, this sleeve being firmly secured to the bulb H by cementing material or other suitable means well known in the art. Another conducting lead I5 is connected to the other end of the lament I2 and likewise extends outwardly through the base of the bulb II and is connected to a central contact member iE that is adapted to engage the central contact of a lamp socket or similar xture.

The sleeve I4 is surrounded by a threaded shell I'I that is adapted to engage the threaded shell of the socket or other fixture into which the lamp is to be inserted. The lower extremity of the shell I'I is formed with an inwardly extending ange portion I8 overlying a shoulder portion I9 of the shell I'I. The upper extremity of the shell I'I is also formed with an inwardly eX- tending flange portion 20 which lies within an annular groove ZI extending around the periphery of an annular insulating member 22, The flange 20 is loose in the groove 2| to permit free rotative movement between the shell I'I and the member 22, but to prevent axial movement between said members. The central contact member IS is rigidly secured to the insulating member 22 as a support and the member 22 is provided with a suitable hole 23 through which the conducting lead I5 extends to its connection with the member I 6.

The lower or inner face of the insulating member 22 is provided with an integral inwardly pror sulating member 22 if this latter member be held jecting portion 24 which is shown as being of substantially square cross section. This projecting portion 24 extends through an opening 25 in the upper wall of the sleeve or cap I4. The hole 25 is of shape similar to that of the projecting portion 24, but is suiiiciently larger than the projecting portion to permit free sliding movement therebetween. y

A spiral or helical spring 26 is disposed between the top wall of the sleeve or cap I4 and the inner surface of the insulating member 22 and coacts between these members to bias the sleeve or cap I4 and the bulb I I outwardly with respect to the insulating member 22 and the threaded shell I1. It will be apparent that the outward movement of the sleeve and the bulb is limited to the position illustrated in Fig. l of the drawings, in which position the shoulder portion i9 of the sleeve I4 is engaged by the inwardly extending flange I8 at the lower end of the sleeve I4.

A conductor 21 is connected at its upper extremity to the central contact member I6 and extends downwardly therefrom through` a suitable hole in the insulating member I6 to terminate in a contact button 28 on the lower face of the main portion of theinsulating member 22. This contact button 28 is disposed in alignment with one of the convolutions of the spring 26. It will be seen, therefore, that the bulb II and the sleeve I4 may be forced inwardly toward the instationary.

When the bulb II and sleeve I4 are moved in this manner, the flange portion I8 at the bottom of the threaded shell I1 slides over the reduceddiameter portion of the sleeve I4 and the inwardly projecting portion 24 of the member I6 slides through the opening 25 in the upper wall of the sleeve I4. The extent of this movement will be limited by engagement between one of the inner convolutions of the spring 26 and the contact button 23 at the lower extremity of the conductor 21. Such engagement results in a shortcircuiting of the filament I2, since the spring 26 is in electrical contact with the sleeve I4 to which one terminal of the filament is connected, and the contact button 28 is in electrical connection through the conductor 21 with the contact member I6 to which the other terminal of the filament is connected.

Fig. l of the drawing shows the sleeve I4 and the threaded shell I1 connected by a pin 29. This pin may be of suitable size and location to establish such a mechanical connection between the sleeve I4 and the shell I1 that the shell I1 may be screwed into a lamp socket or similar fixture by turning the bulb II. When` the lamp is screwed all the way into the socket, the contact member I6 makes contact with the central contact of the socket to establish an electrical connection from one side of the circuit to one end of the lament I2 through the conducting lead I5. The other side of the circuit is connected to the other end of the filament I2 by contact between the threaded shell of the socket and the shell I1 that is in engagement therewith, and thence by contact between the flange I8 of the shell I1 and the sleeve I4 and through the conducting lead I3 that is connected to the sleeve I4.

After the lamp is rmly screwed into its position in the socket, the bulb may be given an additional twist of sufficient force to shear off the pin 29, thereby breaking the mechanical connection between the sleeve I4 and the shell I1 and `leaving these members rotatable with respect to each other. This is one construction whereby the lamp may be rendered theft-proof, since it is impossible to turn the threaded shell l1 by turning the bulb I I after the pin 29 has been sheared. When it is desired to remove the lamp from its socket it is necessary to break the bulb in o-rder that access may be had to the outer end of the shell I1 with a suitable tool. Upon proper application of such tool, such as pliers or the like, after the bulb I I has been broken the lamp base may be unscrewed from its socket.

It will be seen that the substantially square construction of the projection 24 and the corresponding shape of the hole 25 in the upper wall of the sleeve I4 will prevent relative rotation between the insulating member 22 and the sleeve I4 to which the lamp bulb is secured. The prevention of such rotative movement prevents twisting of the ilament lead I after the mechanical connection between the sleeve I4 and the shell I1 has been broken by shearing of the pin 29. The insulating member 22 then always turns with the bulb, the inwardly projecting ange 20 at the upper end of the shell I1 riding in the annular groove in the member 22.

In lamps of other than the theft-proof type, it is not necessary to permit relative rotation between the sleeve I4 and the shell I1 after the lamp is placed in a socket, and such relative movement may be prevented by any suitable construction which will not interfere with the axial sliding movement between these members. This may be accomplished by making the reduced diameter portion atv the lower extremity of the sleeve I4 of non-round cross section and making the opening determined by the inwardly projecting flange I8 of the shell I1 of similar shape. With this construction it is unnecessary to provide a square projecting portion 24 extending through an opening of similar shape in the upper wall of the shell I1, as this projection then serves only as a guide for the sliding movement of the sleeve I4 and as a bushing to insulate the lead I5 from the sleeve or cap I4 and from the spring 26.

It will be seen that the present invention is admirably suited to be embodied in theft-proof lamps of the type described, since the only additional parts required for the embodiment of the short-circuiting switch are the spring 26, the conductor 21 and the contact button 25, which contact button may be an integral part of the conductor 21. All of the other parts are provided to secure the theft-proof construction of the lamp and only minor changes in the details of construction of such other parts are necessary to adapt the same for the provision of the shortcircuiting device.

In the operation of the device embodying the present invention, the lampY is inserted in its socket in the usual manner, and, in the case of a theft-proof lamp, is given the additional twist necessary to shear the pin 29. If a group of series connected lamps vbecomes extinguished while the external circuit thereto Vis uninterrupted, each of the lamps in the group is individually manipulatedby depressing the bulb toward the base thereof against the action of the spring 26, which spring returns the bulb to its normal position after manual release thereof. In this manner each of the lamps in the group is short-circuited until the one in which the open circuit has occurred is reached.

Upon depression of the bulb of such defective lamp, the circuit through the remaining lamps in the group is reestablished and these remaining lamps will be lighted. Thereupon, the defective lamp is removed from its socket and replaced by a new one. In the event that theft-proof lamps are utilized, the bulb of the defective lamp will be broken and its base removed in the manner heretofore described.

It will be readily appreciated that this method of testing series connected lamps is very much more expeditious than any method heretofore known. Furthermore, this method, when applied to theft-proof lamps, involves the necessity of breaking only the defective lamp in a group, the undamaged lamps remaining in service. It will also be understood that, while the short-circuiting of a defective lamp in a series circuit causes an increased voltage to be applied to the remaining lamps in the circuit, this will not result in injury to the filaments of such remaining lamps because the increased voltage is applied for only an instant during the test.

It is known to be old to embody a short-circuiting switch in the base of a lamp for short-circuiting one of two series-connected filaments in the lamp for the purpose of dimming the light produced by the lamp. Such switches, however, have never been provided with means for returning the same to open position after manual release of the means whereby the switch is closed. These switches are provided for a very different purpose than that of the present invention, inasmuch as they are not adapted to effect the testing of a plurality of lamps connected in a series circuit.

It is also known to be old to provide special lamp sockets with short-circuiting switches therein, and the claims of this application are not to be construed as covering such devices. The present invention accomplishes the objects specified without necessitating any alteration whatsoever in the construction of the standard sockets or other fixtures of the illuminating system to which the invention is applied.

The present invention is believed to be novel in embodying a short-circuiting switch in an incandescent lamp structure, which switch is normally biased toward its open position and isl closed only when the actuating means therefor is manipulated in a predetermined manner and held in such manipulated position. The invention is also believed to be novel in embodying any type of short-circuiting switch in a lamp of the theft-proof type and in embodying any type of short-circuiting switch in a single-filament lamp.

While only one specific embodiment of the invention has been shown and described herein, it will be understood that many changes and modifications may be made in the details of construction and of circuit connections without departing from the spirit and scope of the invention. It is desired, therefore, that the invention be limited only to the broadest aspect of the above indicated features which are believed to be novel.

A preferred embodiment of the invention having been shown and described, what is claimed as new and is desired to secure by Letters Patent of the United States is:

1. In an incandescent electric lamp, a bulb, a filament supported therein, and a base movably mounted on said bulb and including means for short-circuiting said filament upon manipulation of said bulb in a predetermined manner and resilient means also included in said base for filament supported therein, a metallic sleeve secured to the base portion of said bulb and electrically connected to one end of said filament, a contact member electrically connected to the other end of said filament, an insulating member supporting said contact member and located between the latter and said metallic sleeve, resilient means biasing said metallic sleeve and said insulating member apart, and contact means connected between said contact member and said sleeve and engageable upon manipulation of said bulb against the biasing action of said resilient means to short-circuit said lament.

fi. In an incandescent electric lamp, a bulb, a lament supported therein, a metallic sleeve sccured to the base portion of said bulb and electrically connected to one end of said filament, a contact member electrically connected to the other end of said filament and adapted to engage a Contact member of a socket or like fixture, an insulating member supporting said contact member and located between the latter and said metallic sleeve, resilient means biasing said metallic sleeve and said insulating member apart, a screw-threaded conducting shell coacting between said sleeve and said insulating member to limit the movement of said sleeve and insulating member away from each other and disposed in electrical Contact with said sleeve to connect said one end of said filament to the screw-threaded shell of a socket or like xture, and a conductor connected to the contact member carried by said insulating member and adapted to make connection with said sleeve to short-circuit said filament upon manipulation of said bulb against the biasing action of said resilient means.

5. In an incandescent electric lamp, a bulb, a filament supported therein, and a base comprising two substantially concentric hollow cylin- -drical conducting members, one of which is secured to said bulb and is electrically connected to one end of said filament, resilient means biasing said conducting members apart axially, and contact means supported by said conducting members and engageable upon manipulation of said bulb against the action of said resilient means to short-circuit said filament.

6. In an incandescent electric lamp, a bulb, a filament supported therein, and a base comprising two substantially concentric hollow cylindrical conducting members, one of which is secured to said bulb and is electrically connected to one end of said filament, resilient means biasing said conducting members apart axially, contact means supported by said conducting members and engageable upon manipulation of said bulb against the action of said resilient means to short-circuit said filament, and means preventing relative rotation between said conducting members whereby the lamp may be operatively inserted in a socket or like xture by rotatively manipulating said bulb, said preventing means being releasable after the lamp is so inserted, to render said conducting members relatively rotatable, whereby the lamp cannot be removed from its socket or like xture by manipulation of said bulb.

7. In an incandescent electric lamp, a bulb, a ilament supported therein, and a base comprising a substantially cylindrical metallic cap member secured at its open end to the base portion of said bulb and having a reduced-diameter portion adjacent said open end, a substantially annular insulating member coaxially disposed with respect to said cap member adjacent and outside the closed end thereof, a substantially cylindrical shell surrounding portions of said sleeve and insulating member, said shell having at one end thereof an inwardly extending peripheral flange portion overlying the shoulder formed by the reduced-diameter portion of said cap member and having at its other end an inwardly extending peripheral flange lying within a substantially annular groove extending peripherally around said insulating member, a helical compression spring coacting between the closed end of said cap member and the inner surface of said insulating member to bias said members apart to an extent limited by engagement between the rst-mentioned flange portion of said shell and the shoulder portion of said cap member, a contact member carried by said insulating member, a conductor extending from said contact member to the other end of said l'llament, and contact means engaged by depression of said bulb against the action of said spring for connecting said contact member to said cap member to short-circuit said lament.

8. In an incandescent electric lamp, a bulb, a

, lament supported therein, and a base comprising a substantially cylindrical metallic cap member secured at its open end to the base portion of said bulb and having a reduced-diameter portion adjacent said open end, a substantially annular insulating member coaxially disposed with respect to said cap member adjacent and outside the closed end thereof, a substantially cylindrical shell surrounding portions of said sleeve and insulating member, said shell having at one end thereof an inwardly extending peripheral iiange portion overlying the shoulder formed by the reduced-diameter portion of said cap member and having at its other end an inwardly extending peripheral flange lying within a substantially annular groove extending peripherally around said insulating member, a helical compression spring coacting between the closed end of said cap member and the inner surface of said insulating member to bias said members apart to an extent limited by engagement between the first-mentioned flange portion of said shell and the shoulder portion of said cap member, a contact member carried by said insulating member, a conductor extending from said contact member to the other end of said ilament, and contact means engaged by dep-ression of said bulb against the action of said spring for connecting said contact member to said cap member to short-circuit said filament, said shell being externally screwthreaded to engage the screw-threaded shell of a socket or like fixture and being secured against rotation with respect to said cap member to permit the lamp to be screwed into the socket by rotative manipulation of said bulb, but being adapted to be released from said secured relation after the lamp is screwed into the socket or like xture to prevent removal of the lamp by manipulation of the bulb, and said insulating member having a portion engaging said cap member for preventing relative rotation therebetween to prevent twisting of the said conductor extending from the filament to the contact member carried by said insulating member.

9. An incandescent electric lamp embodying means for preventing unauthorized removal oi the same from a socket without destroying the lamp, a filament, an envelope, and manually operable means for short-circuiting the filament associated with the envelope to be operated by manipulation thereof in a predetermined manner, the envelope also being manipulable to render said removal-preventing means operative.

10. An incandescent electric lamp comprising a lament, a base, an envelope for the lament movably mounted on said base, means for preventing unauthorized removal of the lamp from a socket without destroying the lamp, and means embodied in said base for short-circuiting said lament, said removal-preventing means being rendered operative by manipulation of the envelope with respect to the base and said shortcircuiting means also being operable by manipulation of the envelope with respect to the base.

CURTIS J MARTIN. 

